Audio problem 97 blazer

Lets try this again. I posted this yesterday, but there was aproblem with the forums on here and somehow my thread became about pathfinders.

I just spent 6 hours on a deck install into a 1997 chevy blazer. I have been installing for 10 years, and this install had I problem I had not seen before, and have yet to diagnose. Any thoughts?

Installed a Panasoic 7303u into this car. Standard gm harness, no factory amp. Upon installation, everything appeared to be fine. With the ignition on, and the car not running, everything works as it should. Upon starting the car, the speaker level audio outputs cut in and out rapidly. Its almost sounds like a cd skipping, except it does it on the radio as well as the aux in. My first thought was that I had a grounding problem, so I disconnected the one from the harness, and ran a new one to the kick panel. No change. I ran a new one to the battery, with similar results. I ran new power and ground directly to the battery with no results. Still stuck on this being power related, I cleaned up the factory chassis and body grounds. No improvement. Here is where things get wierd. To get the problem to go away, all you have to do is touch the deck. as long as you are touching it, the problem is non-existent. You need not even be touching the car while you touch the deck for it to go away. You can stand outside of the car and lean in without making even the slightest contact with the car, and the problem goes away. I tried this with 2 panasonic 7303u head units, 1 panasonic 8303u headunit, a blaupunkt laguna, and a clarion mc855. The Blau and the Clarion had no problems whatsoever. Just panasonics. Here is a list of what I tried to fix the problem. Please let me know what you think. BTW, I ended up selling him into the clarion, and everything works fine. This is just for future referrence. Also, all of the panasonics work fine in other cars.

New grounds,

New power

Cleaned factory grounds

Verified correct impedence on each channel (4 ohms)

checked for shorts on speaker wires

tried several head units

checked for AC ripple on power (found there to be a ripple of .43 milivolts AC present at radio harnes power wire. I don't know off hand what the acceptable limit is, but I imagine this is acceptable.)

Added Diodes to power, ground, and switched wires (just grabbing at straws)

Any other ideas?

Anyone?

3 defective head units? in a row? that all work in fine in other cars?

Thats as good an explanation as any I came up with tho.